In the manufacturing of extruded products, it is generally desirable to attain the purest of extrusions with the least amount of degradation of the molten polymer. This is especially true for products for optical film applications. If even small regions within the melt flow are allowed to re-solidify or dwell overlong in the molten state, specks or streaks may appear in, e.g. the extruded optical film. This may make the film useless for its intended purpose.
Conventionally, as the melted polymer resin flows through the melt system, it may go through one or more gear pumps, filter packs, or melt blocks, interconnected at connection points to form a flow channel. Variable temperatures of connection points or slight mismatches in the alignment of connection points may cause a disruption of resin flow. The residence time of the melted resin will increase dramatically in any area where there is a disruption in flow causing the melt to either re-solidify or degrade and char. As virgin melted resin continues to flow through the melt channel, small particles of re-solidified and charred material may break off, causing imperfections in the finished product.